


The day the truth came out or: The heat was to blame

by TheGhostInTheMachine



Category: Shadowhunters (TV), The Shadowhunter Chronicles - All Media Types, The Shadowhunter Chronicles - Cassandra Clare
Genre: Alec Lightwood Deserves Nice Things, Alec Lightwood Loves Magnus Bane, Angst and Humor, Attempt at Humor, Bad Puns, Boys Kissing, Established Relationship, Gay Alec Lightwood, Happy Ending, How Do I Tag, M/M, Magnus Bane Deserves Nice Things, Magnus Bane Is A Freewheeling Bisexual, Magnus Bane Loves Alec Lightwood, Magnus Bane has a bad reputation, Maryse Lightwood Being An Asshole, POV Alec Lightwood, POV Isabelle Lightwood, POV Magnus Bane, Protective Isabelle Lightwood, Virginity, a bit angsty, but it also kinda is, forgiving Magnus, kind-hearted Magnus, not really series compliant, sweating
Language: English
Status: Completed
Published: 2019-05-18
Updated: 2019-05-18
Packaged: 2020-03-07 09:56:23
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 5
Words: 2,859
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18870880
Author URL: https://archiveofourown.org/users/TheGhostInTheMachine/pseuds/TheGhostInTheMachine
Summary: "She looked slightly annoyed now which just confused him and so he took a deep breath before he talked again.“So spill.”She deflated slightly and now just managed to look sad before she opened her mouth.“I’m so sorry, Alec. But there’s something I need to tell you. I just wish…It’s just…”“Isabelle!”She basically yelled her next words as if to get rid of them as fast as possible.“Magnus is cheating on you!”The silence that followed was sickening.





	1. Chapter 1

**Author's Note:**

> As always: English isn't my first language.   
> So please have mercy if you find any mistakes.   
> Enjoy :)

It had been a fairly normal day at the institute so far apart from the fact that it was without any doubt one of the hottest days of the year.

With their recent luck, the air conditioner was also broken.

It was in lack of another expression:  a testing time for all of them.

 

The panting sounds of the training Shadowhunters echoed through the building. 

Demon activities had been higher since Valentine had gotten hold of the cup, a fact that made intense training more essential than ever.

The sun was shining particularly intense today, which to be fair could heat some tempers up.  

 

Jace and Clary were training; their hair was sticking on their skins.   

 They were so focused that they barely registered a fairly annoyed seeming warlock walking past them with an equally unnerved looking Maryse hot on his designer heels.  

The only one that had noticed it and was as subtly as possible, following them, was Isabelle.

 

Ever since Magnus and her brother Alec had become a couple, she had been nothing but supportive of them. 

But if she was honest, deep inside, she was immensely worried.

Don’t get her wrong. 

 

She was extremely proud of her big brother coming out and finally standing up to their parents.

But the stories she had heard about Magnus…

Being far from naïve, she had never believed that there was a chance that the eccentric warlock was a virgin, especially while having lived for over 800 years. 

 

But the list of the people he had warmed his bed with had been nothing less but stomach dropping.

 As far as she knew, Alec had never been in a relationship with anyone, having been as repressed as he had been.

And being the sensitive soul he was, he also had never been intimate with anyone either.  

 

Now having his first boyfriend with whom he had only been together for three weeks now, must have been scary.

Alec being the overthinker he was, would certainly wait and want to plan everything thoroughly before doing the next step.

So all of this didn’t help her calm her fears. 

 

Isabelle couldn’t help but think about if Magnus would eventually get tired of waiting for her brother to be ready for the next step? 

What if he would get what he needed elsewhere?

She was only sure of one thing. 

 

It would inevitably break Alec.

Her big always frowning brother, always acted like nothing could touch him like he was made out of stone.

But she knew him way before he had perfected this mask.

 

Alec was a big softy.

He was the first one to feel empathy for others or cry when something really bad had happened.

When they had been children, she sometimes caught him in such moments.

 

He was always embarrassed by it and always refused to talk about anything that was bothering him.

This was still the case today.

Frankly, it was maddening.

 

So what would happen if the one person that didn’t belong to the family, he chose to trust, would betray him?

Isabelle knew exactly what would be happening.

He would shut down. 

 

Completely. And even maybe forever.  

So who could blame her when she decided to follow Magnus and her mother and did a little bit of eavesdropping?

It surely couldn’t hurt.

 

Right?


	2. Chapter 2

When Alec came back to the institute, his mood got instantly better.

He had been sent to what seemed like a vampire den, which was just a false alarm in the end.

 And for that, he had been in the brutal heat, for six horrific hours.  

 

Not that the temperature was much better inside but at least he was out of the direct sun and away from mundanes.

 Alec groaned when his neck made this all too familiar popping sound, stretching it.

 He was way too tense.

 

A massage could help.

With that thought, a smile came almost automatically on his face.

Just a few days ago Magnus had given him a really professional massage that had really helped him.

 

The result or better what it had ultimately led to had also been not bad.

Far from it.

 The young shadowhunter sighed.  

 

 Could someone die from happiness? If that had been the case he would be the most dead person alive. 

Ugh, what a sappy thought.

If Izzy could hear him, he would never hear the end of it.

 

Speaking of the devil, there at the end of the room, he saw his little sister, seemingly in deep discussion with Jace and Clary about something.

He just wanted to walk towards them when something sparkly caught his eye.

 Magnus was just walking towards the exit.  

 

With one last glance at his sibling, he figured they could keep discussing without him, shrugged and went after his boyfriend.

The warlock was definitely fast.

He strove with a clear intention towards the door but Alec was faster. 

 

Grabbing one arm of Magnus he gently stopped him.

At first, the warlock’s gaze was hard but as soon as he realized who had stopped him, his eyes softened and he smiled softly.

“Alexander. What are you doing here? I didn’t count on you being back here before the evening.” 

 

Loosening his grip on the arm to gently start to caress it to the shoulders, he huffed.

“It was just a false alarm.”

Magnus lifted one hand to put it on Alec’s cheek, his thumb softly moving over the cheekbone.  

 

 “Poor Baby. I can’t imagine how that must have been. Alone the heat…”

He put his other hand on his chest and made a mocking shocked face.

Alec, being used to this kind of teasing by now, didn’t much more than lifting his brows.

 

Then a thought came to his mind. 

He grinned.

“You have really no idea.” 

 

With that, he took the remaining steps between them so that they were so close that he could feel Magnus’ breathing on his face.

“Do you know what’s even worse? My neck. And my shoulders oh and my back. They are all so tense. It’s horrible.”

Meanwhile, Magnus had a knowing look on his face. 

 

But decided to humor him. 

“Oh is that so?”

Alec nodded enthusiastically while angling his face down. 

 

 “Yes. And you know what could help?”

The warlock’s hand that was still on Alec’s cheek wandered a bit towards the hair on the back of his head. 

“I have my suspicions.” 

 

Alec always revelled in the fact that he could affect the old warlock so much.

Hearing his voice getting deeper and deeper with each sentence was really doing things to him.

So the only thing he could do next was humming while finally closing the gap between their lips.   

 

The kiss started innocent enough.

Or it was like that until Alec chose to move forward in the direction of the wall behind Magnus, what apparently startled said man who in response gasped.

This gasp led to Alec moving his tongue into his boyfriend’s mouth and there the innocence ended. 

 

Magnus moaned approvingly and gave just as much back as he got.

They stayed like that for minutes until they reluctantly stopped.

Putting their foreheads together, they waited together with closed eyes for their breathing to return to normal.

 

Finally still, being only inches apart from each other, Alec opened his eyes first.

“Do you have to leave?”

Magnus smiled while opening his eyes as well.  

 

“I wanted to but you know with you being here now, I don’t think I have actually a reason anymore so…”

The shadowhunter leaned back to grab Magnus hand.

“So… come with me?” 

 

 Magnus lifted their clasped hands to his mouth to press a kiss to Alec’s.

“Lead the way.”


	3. Chapter 3

 Together they walked towards the others.

They were immediately quiet when the couple arrived.  

The atmosphere was with the lack of a better word: tense.

 

Alec instinctively let go of Magnus' hand to cross his arms. 

With a frown, he laughed nervously.

“What’s going on guys?”

 

For a few painful seconds, none of them said anything.

Alec was surprised to notice that the usually oh so cocky Jace seemed uncomfortable.

That made him swallow hard. 

 

Clary just looked sad and Izzy looked part angry and part pitiful.

He risked one glance in Magnus’ direction only to see him mirroring his own frown.

Alec had enough. 

 

“So?”

 All three of them shared a meaningful look which resulted in Alec rolling his eyes, slowly getting annoyed and finally Izzy taking one step forward towards them.

He raised his eyebrows and put his hands on his hips as he waited for her to finally open her mouth. 

 

She looked a few seconds to Magnus who in return just looked even more confused than before and then back to Alec.

His sister then straightened her back and looked defiant.

“Can I talk with you for a second?” Glancing again at his boyfriend she added: “Alone?”

 

He basically felt Magnus tensing beside him and he couldn’t bear it.

“Um honestly: No. Whatever weird thing is going on here, I don’t care. However, I care about the fact that you can’t seem to stop looking at my boyfriend, which really rubs me the wrong way, by the way. So whatever you or Jace or Clary have to tell me, they can well damn do that in front of him.”

Izzy seemed genuinely taken aback by his outburst and Jace and Clary had at least the decency to look somewhat ashamed at the floor. 

 

He took a moment to just look at Magnus who was already looking at him with such a font look on his face that he had to force himself to look back at his sister.

She looked slightly annoyed now which just confused him and so he took a deep breath before he talked again.

“So spill.”  

 

She deflated slightly and now just managed to look sad before she opened her mouth.

“I’m so sorry, Alec. But there’s something I need to tell you. I just wish…It’s just…”

“Isabelle!” 

 

She basically yelled her next words as if to get rid of them as fast as possible.  

“Magnus is cheating on you!”

The silence that followed was sickening. 

 

Alec was in shock and couldn’t hear much beside the ringing in his ears.

He blamed that for saying the first stupid thing that came to his mind while looking at Magnus.

“When do you have time for that?!”

 

 His boyfriend, who was practically scowling by now, pursed his lips.

 “That’s an excellent question, dear.”

With that, the warlock turned towards Izzy.

 

“So…Isabelle, if I’m allowed to ask: what did you hear me say that made you come to this conclusion?”

 This reaction was clearly not what she had been expecting.

 She suddenly seemed unsure and licked her lips before answering. 

 

“Well, I mean it was just…you have basically implied that you have had sex with a male or males recently.” 

All eyes were on Magnus who seemed to think.

Then suddenly his eyes grew wider than they had ever been.

 

“Oh.”

Watching the color rising onto the warlock’s face was beyond fascinating.

All tension went out of Alec’s body. 

 

He almost felt giddy.

Watching Magnus becoming more flustered as the seconds went by, made it even worse.

So he couldn’t actually be blamed for what he did next. 

 

Alexander Lightwood burst into laughter.

He laughed so hard that he even started crying.

This resulted in Magnus looking worried and the others being unsure if he needed help.


	4. Chapter 4

_Earlier…_

Being summoned on his day off was bad enough.

Being summoned on a day where he had to leave his apartment where he actually had air conditioning was worse.

Being summoned by Maryse Lightwood was the worst. 

 

Magnus was on edge. 

Normally he would only wear a silk blouse on such a hot day, but having to face Maryse took that option away from him.

He needed armor.

 

This meant for him to wear three (!) layers of clothes plus perfect makeup and styled hair.

He thought he could die while feeling disgusting. 

Being a warlock didn’t make him immune to his clothes sticking to his skin.

 

Not that he led anything show while walking in front of Alec’s mother.

 She had called him earlier to renew the wards.

Something that had the highest priority and just couldn’t wait.  

 

Normally such a visit would at least be brightened or bearable by seeing Alexander but he was out on a mission.

So not only had he to endure her and the disgusted way she was looking at him but no he also couldn’t even let Alexander make that feeling such an encounter left, go away.

Right now she was just watching him as he strolled towards her after having done perfect work.

 

He felt exhausted and was even a bit dizzy.

Since he and Alexander were an item, he always made sure to put his whole strength into his work at the institute. 

Not that anyone would thank him.

 

Well, no one besides Alexander.

When he reached her, she immediately began to write a check, which suddenly didn’t feel right to him.

This woman, how intolerable she might be, was the mother of the love of his life.

 

If and only if Alexander endured him for a while longer then maybe one day- he couldn’t believe that he let even think himself that-she could become his mother in law.

And then she would be family.

Taking money from his family always felt wrong to him. 

 

Using his powers to protect then wasn’t a service to him.

It was a duty.

So that’s why he did what he did next.

 

Gently he lifted his hand to get her attention what surprisingly worked.

“Leave it. It was my pleasure to help the institute.”

She stopped writing and straightened her back after having leaned down to write until now.

 

Maryse raised an eyebrow mockingly.

Suddenly he became nervous.

The way she was looking at him right now wasn’t good.  

 

She lifted one corner of her mouth so that she was basically smirking.

“I didn’t know you had it in you.”

He honestly didn’t know what compelled him to answer as he did.

 

Maybe it really was the way she was looking at him like he was a monkey that just had done something funny or her tone that sounded like it was the most ridiculous thing on earth to her.  

Or maybe it really just was the damn heat that made even his hair that he had been styled to stand upright, partly falling into his eyes.

Later he genuinely didn’t know why he said it.

 

With a smug grin, he opened his mouth.

“You know, lately I had a lot of new things in me.”

 This made her immediately glare at him which he had counted as a win back then.


	5. Chapter 5

Alexander still hadn’t stopped laughing.

This was partly adorable and partly really concerning because Magnus didn’t know why he laughed.

Was it because he couldn’t believe it that Magnus cheated on him or because he couldn’t believe that their relationship had been existing for that long.

 

 Just as he had decided to put a stop on it, Alexander suddenly gasped for air and looked first at his sister and then at him.

Magnus was relieved to notice that his boyfriend looked amused, nothing more.

“What exactly did you say to her?”

 

This made him scrunch his nose.

He only could hope that Alexander was going to be understanding for practically outing his newly not-virginal-state to his mother with one sentence.

Or maybe if they were lucky enough, she jumped to the same conclusion as her daughter. Hm.

 

“I may have said something about having had some things in me lately.”

He squinted his eyes while waiting for Alec’s reaction.

Magnus didn’t have to wait long.

 

A moment later, Alexander let out a laugh that sounded more like wheezing but who cared?

“You’re not mad?”

This made him stop and look at Magnus.

 

“Thrilled? No. But I’m not mad. Just maybe don’t ever mention something that concerned our sex life to my mother or even when she is in hearing range. Okay?”

He still looked mostly amused and so Magnus finally relaxed while nodding.

“Of course, I’m sorry.”

 

Then they smiled stupidly at each other before turning towards the others who looked shell shocked.

Jace seemed to be the only one that was still capable to speak.

“So… what?! He was talking about you?! I mean what?! When did you?! What?!” 

 

They shared a look while they waited for him to come around.

Then Jace looked at Magnus.

“I mean I’m truly sorry. We really should have just assumed… I mean-“ 

 

Magnus stopped him by lifting one hand-this seemed to be a family trait.

 “It’s fine. You’re all forgiven.”

Jace nodded and then looked at Alec, having the most vulgar grin on his face. 

 

“So- what can I say? Respect.”

Alec rolled his eyes in response but still couldn’t help but incline his head as a thank you. 

 

In the end they all would say that the heat had been to blame.

**Notes for the Chapter:**

> So this was my first Malec fanfiction :)   
> I hope you enjoyed reading it as much as I did enjoy writing it.   
> Kudos are life so please don't hesitate <3


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